SULFUR Bosses: Full Boss List and How to Beat Each One

Each area in SULFUR ends with a boss except the Sewers, players report: the Caves, Town, Dungeon/Castle, Forest, Fortress, and Desert each gate your run behind a fight, and clearing the last one completes a playthrough. A community wiki's boss category documents six named bosses: Cousin, Desert Claus, St. Lucia, Terrorbaum, and The Emperor, plus the Town boss encounter. Below is each fight with a strategy, drawn mostly from a player video that demonstrates each boss (550+ hours claimed by its author), a Steam discussion thread, and patch notes.

The SULFUR bosses list

Boss-by-boss strategies

Cousin (Caves)

Cousin has 5,000 health and pops up from one of four mud puddles — body or arms — between attacks. A build dealing over 5,000 damage in one shot (a strong Arbiter hit around 11,000 works) kills him instantly; the player video notes this one-shot has been finicky and buggy since Early Access. If you don't one-shot him, deal a big chunk (aim for under half his health) before he submerges to avoid the baby goblin and spear goblin mob spawns.

His mud shell blocks damage: any melee, shotgun, or automatic weapon strips it. His mud balls hurt a lot on direct hit and can drop food, 9 mm ammo, gun insurance (about a 25% chance per kill, per the video's author), cookbooks, and treasure, making him a great farm target. Keep moving the entire fight.

Town boss trio (Town)

This fight is three oversized minigun gatling enemies, which the video author notes are the only enemies with the teleport mutation, often carrying hidden fire, poison, or explosive mutations on Town 5 runs. Bring soda (or craft it from sugar and water) or health potions to cleanse poison and fire. When you step into the arena and the boss music plays, one always spawns on the left; set up to kill it first.

They have 400 health each and split into smaller versions when killed, so play them like the normal gatling enemies. Use range weapons — close shotguns waste the arena's space — and camp a safe corner while hunting the other two. An ammo-filled room right before the arena lets you stock up, and the area afterwards drops manytermite weapon chests and treasure.

St. Lucia (Castle)

St. Lucia is a multi-phase fight. In her web-line stage, crossing her lines slows you, she spawns moped-riding dagger cronies and homing ghosts, and shooting her does nothing — play for her phases instead.

When the room goes dark, stop moving entirely, find the spawned eyeball, and shoot it before it burns you; botching it just spawns another. Her eyeballs are easiest to hit when she floats above the body pit holding them in front of her. A joel mustard drink gives 100% crit chance aiming down sights for 15 seconds (double damage), which the video author calls very effective against bosses.

The author also warns she has historically glitched into an invulnerable state, so be careful with burst timing — you want her to enter her next phase rather than break her thresholds mid-animation.

Terrorbaum (Forest)

The "German Christmas tree" launches baby crows (bring a bird gun), rushes and ground-pounds, and pings across the arena. You damage him by shooting his eyeballs. In one phase he launches the very bullets you shot at him back at you — move constantly, and note he speeds up as the fight goes on. Elemental bullets get returned too, so avoid standing in your own thunder or fire returns. The video author rates him the best-designed fight and recommends any accurate gun you're comfortable with at range; getting rushed at close range into his ground pound hits extremely hard.

Fortress boss (Fortress)

The Fortress boss's first phase requires shooting the individual targets on his body — the video author's one-shot Breacher build (~22,000 damage) kills each other boss in the game but not this phase, only the second. The strategy is simply to destroy each target while surviving his attacks, then unload on the second phase like any other boss.

Desert Claus (Desert)

Desert Claus endlessly spawns waves of spinning and melee enemies, which is why players on the SULFUR Steam discussions struggled with attack windows and the arena's pushback. The consensus there: kill each mob before the next wave spawns, then focus the boss — he'll eventually give you openings. Bring more firepower: a shotgun with projectile oil and a fire+fire explosion enchant, or a crusader (plague+light) scroll, or a .50 BMG "boss killer" — the Arbiter is easier to use for huge damage, while the Breacher hits even harder but is more awkward. Running away doesn't work; the arena shoves you back into the mob army.

The Emperor (endgame)

The Emperor has 8,000 health, but you can't simply melt him: damage only counts against his red balls, each has a damage threshold, and you must break each one — no one-tapping him. He launches drunk, zigzagging rockets you can shoot down mid-flight, spawns ghost dog samurai, and swings his spider chair for massive damage. The video author calls him the hardest boss in the game and suggests movement speed items while backing up constantly. Players report his reward table is the richest of any fight: two scrolls that reportedly always drop, plus a chance at a 12-gauge chisel, gun insurance, cookbooks, other chisels, and rare guns.

Useful tips from players

• One-shot builds: The video author demonstrates a ~22,000-damage Breacher one-shotting each boss he fights except the Fortress boss's first phase, which must be cleared target by target.
• Boss phases: When bosses drop below health thresholds they become briefly invulnerable while they transition. A Nexus Mods utility called Boss Phase Vulnerable (v1.1.0, updated 2026-11-02) removes this invulnerability — with a deliberate exception for Terrorbaum — for players on the BepInEx framework.
• Novanian Guard (Dungeon/Castle miniboss) breaks like his Castle counterparts: shoot the mask; sunglasses spare your screen. As of patch 1.0.1 he grants 16 XP and is immune to electricity.

Next steps

• The beginner guide covers the Early Access-era basics (insuring weapons, soda crafting, Ralphie's store) that the boss strategies above assume you know.
• The item attributes page helps you build the .50 BMG and oil-enchanted weapons the desert and endgame fights demand.
• The walkthrough gives area-by-area routing so you reach each boss with ammo to spare.

FAQ

How many bosses are in SULFUR?

Each area ends in a boss except the Sewers, players report: Cousin (Caves), the Town trio, St. Lucia (Castle), Terrorbaum (Forest), the Fortress boss, Desert Claus (Desert), and The Emperor at the end. A community wiki lists six named boss pages, and the video author confirms the Sewers have none.

How do you beat the desert boss?

Per the Steam discussion, kill each wave completely before the next spawns, then damage Desert Claus during his openings. A .50 BMG Arbiter or Breacher, or a shotgun with projectile oil and fire+fire explosion, provides the burst you need.

Can you one-shot bosses in SULFUR?

The video author demonstrates a ~22,000-damage Breacher one-shotting each boss except the Fortress boss's first phase, where you must destroy individual targets; Cousin dies to anything over his 5,000 HP in a single hit, while The Emperor's red-ball thresholds block one-shots entirely.

Is there a mod that stops bosses going invulnerable?

Yes — Boss Phase Vulnerable on Nexus Mods (checked 2026-11-06) removes the threshold-based invulnerability, except for Terrorbaum, and requires the SULFUR BepineX Framework.

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Check note: Boss list and encounter strategies come from first-hand player material — the "How to Beat Every Boss in SULFUR" video by a long-time player and the Steam discussion on the desert boss — plus the official SULFUR Steam page for patch notes, achievements (including "Beat the Goblin Cousin"), and the 1.0 launch details. The community wiki's six-boss category count reflects December 2024 Early Access data and may be incomplete for 1.0; exact boss health values beyond those stated in the video remain unconfirmed.